Manufacture of drawn glass



l. o. PEDERSYEN MANUFACTURE 0F DRAWN GLASS Filed Aug. 5l. 1929 QNI , lio

` applications referred to above.

Patented Jan. 3, 1933 UNITED STATES PATENT oFFicE Application illed August 3l, 1989.. Serial No. 889,822.

My invention relates to the die drawing of glass from a molten glass bath for forming sheets, hollow articles, tubin ,etc The present invention relates particularly to after 5 treatment of such die-drawn articles in order to make them stronger and less liable to breakage.

The drawing methods for producing such articles are set forth, for example, in my copending application Ser. No. 310,279, filed October 4, 1928, and in the co ending application Ser. No. 369,271, filed une 6, 1929, of Pedersen & Byrnes.

Figure 1 is a vertical central section of a present preferred embodiment of the apparatus for practicing the invention in the drawing of cylinders, and

Figure 2 is a partial section of an appa ratus for drawinlg sheet glass.

Referring to adapted to receive a reversible pot 12 which is supported by trunnions 13. The furnace is rovided with burners indicated schematica y at 14 for maintaining the glass 1n the pot 12 at the proper temperature. A. formlng die 15 is supported above the surface of the molten mass 'contained in the pot 12 by means of an arm 16 which I iind it convenient to secure to a bracket' 17. The actual structure of this portion of the device is omitted since it is not part of the present invention.

A bait 18 is carried by suitable actuatin mechanism which permits it to be raised and lowered. vThe bait 18 is hollow so that air under pressure may be passed therethrough.

In operation, the bait 18 is lowered through the die 15 into the'molten mass of glass in the pot 12. The `die 15 may be made up of a number of portions and these portions may be retractable asA disclosed in t e copending After the bait 18has secured a hold on a portion of the molten glass, it is raised slowly and the air pressure supplied therethrough causes the drawn glass to be formed hollow. As the bait is raised further, the outer surface of the hollow shape adhering to the bait engages the forming die 15. As mentioned above, the

igure 1, a furnace rests on suitable foundations 11. The furnace is i die is so positionedwith respect to the surface of the glass in the pot 12 that it exerts ah forming and 'sizing effect on the drawn s ape. y

In Figure 2, I have shown a somewhat similar apparatus except that it is adapted especiall for drawing a continuous g ass sheet. In igure 2, a drawing chamber 20 is formed in the forehearth of a glass-melting furnace by means ofthe roof 21 covering the fore-)'- hearth and the side walls 22 depending from the roof. Above the drawin chamber a vertical annealing leer 23 exten to any desired height. Burners 23a su ply heat to the annealing leer. .At s ace intervals alon the length of the leer, riving rolls 24 are p aoed to move the drawn sheet upwardly. After the sheet has reached the top of the leer, it is cut into lengths after the usual manner.

The sheet-drawing apparatus of Figure 2 includes a pair of forming dies 25 and 26, as

well as adjustable coolers 27 and 28. This A apparatus is described and claimed in the copending application, Serial No. 369,271, referred to hereinabove and is shown herein merely as an example ofthe application of the present invention. v l

After the cylinder or sheet has been drawn from the pot or drawing chamber and cut into sections of suitable length, I subject these sections to a heat treatment which com rises slowly raising the temperature thereo to a value in excess of the critical point. After this temperature is reached, I slowly cool the sections to atmospheric temperature. Experiment has shown that, by heating the section slowly to a maximum temperature of 1000 F., the resulting product is of very good quality, free from internal strains and capable of withstanding a considerable degree of roughchandling.

Although I have illustrated and described herein only two modifications of apparatus for practicing my invention, it is to be un- ,i derstood that changes and alterations may be `made therein within the scope of the appended claims, the-terms of which are the only limitations to be imposed on the scope ofthe invention.

2 l memos I claim:

1. In the manufacture of glass articles, the steps consisting of continuously drawing tubular glass in contact with a forming die,l

5 cutting said drawn tube into setctions, slowly raisin the temperature of each section above the cr1tica1 point, and then reducing it slow- 1y below the critical point.

2. In the manufacture of glass articles, the

steps consisting of continuously drawing glass in contact with a forming die, cutting the dra-wn glass into'sections, slowl raising the temperature'of each section a ove the critical point, and then reducing it slowly below the critical point.

In testimony whereof I have hereunto set my hand.

INGVALD O. PEDERSEN. 

